We have continued the development of 13C NMR isotopomer methods for diagnostic applications. Significant advances include the first use of HMQC-TOCSY for measurement of anaplerosis and substrate oxidation, the first application of HMQC-TOCSY for quantitation of citric acid cycle kinetics from tissue extracts, and the demonstration that high quality 13C NMR spectra suitable for isotopomer analysis can be obtained in humans from urinary phenylacetylglutamine, acetaminophen glucuronide or blood glucose. A broad range of problems related to hepatic intermediary metabolism which previously could be addressed only with radiotracers can now be handled with stable isotopes. (Core 2) REPORT PERIOD: (09/01/97-08/31/98)